Japanese Patent Application Publication No. 2008-171783 discloses a fuel cell in which, as shown in FIG. 9, a membrane electrode assembly 4 formed by joining an anode 2 to one surface of a solid polymer electrolyte membrane 1 and joining a cathode 3 to the other surface thereof is held by an anode-side separator 5 and a cathode-side separator 6. A passage for supplying a hydrogen-containing gas to the anode 2 is formed in the anode-side separator 5 while a passage for supplying an oxygen-containing gas to the cathode 3 is formed in the cathode-side separator 6.
Moreover, the solid polymer electrolyte membrane 1 is held by first supporting members 7 and second supporting members 8. The first supporting members 7 are integral with the anode-side separators 5 and are in contact with the solid polymer electrolyte membrane 1 outside electrode ends of the anode 2 in a plane direction. The second supporting members 8 are integral with the cathode-side separator 6 and are in contact with the solid polymer electrolyte membrane 1 outside electrode ends of the cathode 3 in the plane direction. In the fuel cell, a recessed portion 5a is formed in a peripheral edge of the anode-side separator 5 and an O-ring 9 is fitted into the recessed portion 5a to seal the gases.